[LLVMdev] Building uclibc ...

[Dound]

On 9/12/07, Chris Lattner <sabre at nondot.org> wrote:
>
>
> On Sep 12, 2007, at 3:56 PM, Dound wrote:
>
> On 9/12/07, Chris Lattner <sabre at nondot.org > wrote:
> >
> > On Wed, 12 Sep 2007, Dound wrote:
> > > I am trying compile a libc with llvm (currently uclibc).  I am able to
> > > compile uclibc by changing the Rules.mak to use llvm-gcc, llvm-ar,
> > llvm-ad,
> > > and not using strip.  (I also use the --emit-llvm flag for
> > llvm-gcc).  When
> > > I run llvm-nm on libc.a (or try to use libc.a) I run into
> > problems.  For
> > > example, strlen is not defined -- llvm-nm shows that strlen.os has
> > > __GI_strlen while if I compile with the "normal" tools (gcc, ar, ...)
> > > strlen.os has __GI_strlen as well as strlen listed (both have the
> > symbol
> > > value 00000000).
> > >
> > > Any ideas why the archive I create with llvm doesn't define the strlen
> > (and
> > > most other) symbols but does define the __GI_strlen?
> >
> > Can you paste the output of nm for the native GCC version?  It's
> > possible
> > that uclibc is using aliases for these, and it seems very likely that
> > llvm-nm just isn't printing aliases at all.  Anton, do you want to see
> > if
> > llvm-nm should be extended by this?
>
>
> Sure, thanks for your thoughts ... it is a little long so I'll just
> include links to the nm output:
>
> nm on the gcc generated native archive:
> http://www.dound.com/tmp/nm-native.txt
> llvm-nm on the llvm generated archive:
> http://www.dound.com/tmp/nm-llvm.txt
>
>
>
> Okay, this doesn't look like an alias issue :).  WIthout more information,
> I can't tell what is going on.  Please build the file that produces
> strlen.os with the -E option to get preprocessed output, and attach it to
> a bugzilla entry.  With that we can figure out what is happening.
>
> Thanks,
>
> -Chris
>

Thanks, I  have submitted this to bugzilla (#1655 --
http://llvm.org/bugs/show_bug.cgi?id=1655).  I have included in that report
an attachment of the object code generated for one particular function
(strcpy) from both GCC and LLVM.  I also include the preprocessor output
from both (-E) as well as the preprocessor output from LLVM after I make a
change to an input file (described in the report #1655) since with that
change I am able to get both GCC and LLVM to produce the symbol I need, e.g.
T strcpy.

The diffs between the GCC/LLVM outputs and the two LLVM preprocessor outputs
is pretty small, so hopefully someone who is knowledgeable about LLVM will
be able to figure out what is going wrong (or what I'm doing wrong).

Thanks again for the help!

~ David
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